The Tasmanian External link: LegislationWeed Management Act 1999 provides for the management of declared weeds and promotes a strategic and sustainable approach to weed management in Tasmania. Once a weed has been declared, a draft weed management plan must be compiled within 12 months of the declaration.

The declared weed list is essentially a priority list of weeds of State significance to specify where limited resources and management efforts should be directed.

Thus, the number of weeds listed provides a measure of management effort. That is, the greater the number of weeds declared on the Act, the greater the potential management effort required to limit their spread and manage their impacts. However, plants may be declared under the Act that are not here, or whose populations have not changed, but whose threat is recognised: the actual threat has not changed, merely its recognition.

The Tasmanian External link: LegislationPlant Quarantine Act 1997 contains a List A and List B. These lists catalogue various pests and diseases that threaten Tasmanian plants and animals. The aim of the lists is to contribute to regulatory efforts to protect Tasmania's horticultural and forestry industries as well as the natural environment. List A consists of pests and diseases that we usually do not have present in the State and would pose a significant risk to our plant industries and/or environment if they were to become established. List B pests and diseases usually are already present in the State, but may not be widespread.

The number of pests and diseases listed on List A and List B provide a broad indication of any trends in introduced species that threaten, or may threaten, our environment. However, de-listing of species from List B does not necessarily indicate that they pose a reduced environmental threat, but that they have become well established and widespread in the State.

In November 2009, there were 102 plants and plant aggregates declared as weeds under the External link: LegislationWeed Management Act 1999. Statutory Weed Management Plans specify the restrictions or management measures required for each of the declared weeds (as required under the Act). These weeds are classified as being either being agricultural or environmental weeds.

The number of Declared Weeds listed in the Tasmanian Weed Management Act 1999

The following downloadable file lists exotic plants that were listed as declared weeds in 2007 under the Tasmanian Weed Management Act 1999 into agricultural or environmental weeds. At the time, 68 declared weed species were identified as having a known impact on the natural environment. The file is available as a Microsoft Word document through the link: List of Declared Weeds in Tasmania under the Weed Management Act 1999, June 2007.

DPIPWE has also developed a web-based 'Weeds Index'. This website provides information on weeds in Tasmania, including images for identification, information sheets, control guides and management plans where they have been developed. It also identifies the 102 weeds that have been declared species under the Weed Management Act 1999 in an effort to identify those weeds that property managers are required by law to control. The Weeds Index can be accessed through the External linkDPIPWE website.

Weeds are also declared under other Tasmanian legislation. In April 2008, there were 28 plant pests, 4 fungi, 1 bacteria and 2 viruses listed under Section 10 (List B) of the Plant Quarantine Act 1997. List A plant pests or diseases are those exotic pest and pathogen species not established in Tasmania that are considered to pose the greatest potential threat, whilst List B plant pests or diseases are those classified as being present in the State although they may not be widespread and are usually contained or managed. Since the last SoE Report in 2003, the plant pest white weed (Lepidium draba syn. Cardaria draba) has been listed as a List B as have the fungi clubroot of brassica (Plasmodiophora brassicae ) and onion rust (Puccinia allii). In addition, pampas grasses (Cortaderia spp.) and Brazilian waterweed (Egeria densa) have been moved from List A to List B. The following table identifies plant pests and diseases listed under List B of the Plant Quarantine Act 1997 as of April 2008.

Of the seven weeds of national significance (WONS) that are listed as being present in Tasmania, blackberry (Rubus fruticosus), boneseed (Chrysanthemoides monilifera), gorse (Ulex europaeus), serrated tussock (Sus scrofa) and willows (Salix spp.) are listed under List B of the Plant Quarantine Act 1997. Bridal creeper (Asparagus asparagoides) and Chilean needle grass (Nassella neesiana) are listed under List A of this Act.

Since the last SoE Report , the root rot fungus Phytophthora cinnamomi, chrysanthemum white rust (Puccinia horiana) and powdery scab of potato (Spongospora subterranea) and wilt (Verticillium spp.) have been revoked (de-listed) from List B. In particular, the formal revocation notification for P. cinnamomi as no longer warranting List B quarantine disease status for Tasmania does not indicate that this disease is now under management control. Paradoxically, the de-listing of species from List B does not necessarily indicate that they pose a reduced environmental threat. In the case of P. cinnamomi, the delisting of this fungi from List B is indicative of it becoming well established and posing a potentially greater environmental threat.

In August 2007, there were also 140 prohibited seeds declared under the Seeds Amendment Act 1999 outlined in the Seeds Regulations 2000. Prohibited seeds to Tasmania included those from WONS weed species such as bridal creeper (Myrsiphyllum asparagoides), gorse (Ulex europaeus) and ragwort (Senecia jacobaea), and other weed species such as thistles (Carthamus spp.), Paterson's Curse (Echium plantaginium) and the freshwater Canadian pond weed (Elodea canadensis). The full list of prohibited seeds can be accessed through the External linkDPIPWE website.

An indicator can show trends or changes that apply to one or more environmental issues. The data within an indicator is used to inform an issue report and any related recommendations. A summary of the indicator's relevance to a particular issue can be found within the 'Indicator' section of each of the linked issue reports below.